I became interested in Greek a few years ago. I found lessons on YouTube taught by a pastor using the King James Vible and the Textus Receptus which is the most accurate Greek New Testament.
I gave up for a while but have started to get into it again. I have found Talkbaco and the Freek kekeyboard on my phone to be helpful. I am hoping to learn modern and Koine Greek to be able to read the Textus Receptus.
I have also found DuoLingo to be a good tool. I have other books and tools for Koine Greek.
Check out this book for helpful tips.